Teacher Background

Did you ever wonder why you can respond so quickly when you are startled? Wonder why you can “see” a picture in your mind’s eye? Wonder why you can remember facts, events and skills that you learned or experienced a long time ago? Your nervous system makes these and many more things possible. The brain is the command center of the nervous system; it controls virtually all functions of the body.

The brain of the average adult weighs about three pounds and fills over half the skull. Even though it is soft (like pudding), the brain can be divided into several regions, each with very specific functions.

The cerebrum, about 85% of the brain’s mass, sits above the brainstem and cere­bellum. The surface of the cerebrum, known as the cerebral cortex, has bumps (gyri) and grooves (sulci). The cerebrum enables one to think, learn, reason, remember, feel sensations and emotions, and move muscles purposefully. It is comprised of two hemispheres (or halves), separated by a deep fissure. The hemispheres are connected by a large bundle of nerve fibers known as the corpus callosum. They communicate with each other constantly. Even though the hemispheres may look the same, they are somewhat specialized for certain functions. For example, in most people, the ability to form words is a function that seems to be located within the left hemisphere, while the right hemisphere is better at processing spatial information. Different parts of each hemisphere handle specific functions, including hearing, vision, speech, memory, decision making and long-term planning.

The cerebellum sits at the back of the brainstem and is about the size of a tennis ball. It helps us maintain balance and posture, and coordinates our movements. The cerebellum also plays an important role in our ability to learn and remember new motor skills, such as riding a bike.

The limbic system is comprised of a number of interconnected brain regions, including areas within and under the cerebral hemispheres. It is involved in many emotions and motivations, especially those related to survival, such as anger, fear, and even the fight-or-flight response. The limbic system also plays an important role in feelings of pleasure, such as those experienced from eating and sex.

The brainstem connects directly with the spinal cord and is responsible for automatic functions of the body, including heartbeat, digestion, breathing, swallowing, coughing and sneezing. Automatic functions are present at birth and happen without thinking about them.

The brain’s main communication channel to the rest of the body is the spinal cord. Nerves branch out from the spinal cord and send and receive information.

Functions and abilities develop as the brain grows and matures. The human brain generally reaches close to 80% of its adult weight by the age of two or three, yet it continues to develop throughout adolescence and early adulthood. The region of the cerebral cortex responsible for judgment, organization and reasoning appears to be one of the last brain areas to reach maturity.

Objectives and Standards

Concepts

The brain is the center of thinking, learning, reasoning, memory, the senses, emotions and movement.

The brain has unique physical characteristics.

The brain is specialized into many different areas, each with a different job.

Materials per Group of Students

Materials per Student

Have students conduct the activity in teams of six. For easier management, have two teams carry out the activity simultaneously, possibly as a relay race.

For each team, label each of six large (at least five-liter) containers with a letter, A through F. Place five liters of water in container “A.” Leave the remaining containers empty.

Setup

Prior to class, fill one balloon with approximately three pounds (48 oz, or 1,450 mL) of water for each group of students, and one additional balloon for demonstration purposes. Use a scale to weigh the balloons, or compare the balloons to something that weighs approximately three pounds to estimate when you have reached the desired weight.

Photocopy the pre-assessment, “Know Your Brain?” (one per student). Before beginning the activities, have students complete the pre-assessment individually.

Have students work in groups of four to discuss functions of the brain (with the balloon), and work individually to create timelines.

Procedure and Extensions

Time

Two sessions, 30-45 minutes each

Pre-assessment and brain basics

Distribute copies of the pre-assessment. Without discussion, ask students to answer the questions. Collect the finished sheets and keep them for use with the post-assessment at the end of the unit. (Do not grade the papers.)

Begin a class discussion by mentioning that research scientists have learned much about the brain but that there still are many unanswered questions. Discuss students’ answers to the assessment and tally the answers for each question on a chart at the front of the room. Moderate the discussion, but do not give answers to the assessment. You may wish to make a separate list of students’ questions about the brain.

Show the water-filled balloon to the class. Ask, How is this like a real brain? How is it different? Give each group one balloon filled with water. Have students within each group share ideas. The Recorder should prepare a chart with two columns labeled “Same” and “Different,” and record the students’ ideas. Students may use a permanent marker to draw a picture of the brain on their balloons.

Optional: Provide students with access to a brain model.

Discuss group answers as a class. Some responses might include the following.

Same: Balloon is similar size, similar weight, contains water, fragile.

Different: Balloon is not alive, not made of cells, not wrinkled, without defined parts, not connected to anything.

You also may want to use information listed in "Brain Facts" (see PDF).

Functions of different brain areas

Project “The Human Brain” page. Discuss the different areas of the brain and the functions that are governed by those areas.

Prompt student thinking by asking questions such as, What part of the brain would be involved in planning your homework? (cerebrum) Coordinating your movements when you play soccer? (cerebellum) Controlling your rate of breathing? (brainstem) Feeling angry? (limbic system)

Then have students consider what parts of the brain are involved in different activities. Reading, for example, involves many areas of the brain (visual information and language is processed in the cerebrum; eye movements are coordinated by the brainstem; triggered emotions might involve the limbic system). Have student groups come up with other common activities or functions and discuss which regions of the brain might be working together during these activities. Have groups present their examples to the class.

Brain development timeline

Begin a class discussion by asking, Do you have the same capabilities and skills as when you were born? Which capabilities have you always had? Encourage students to think about automatic functions, such as breathing, or senses, such as hearing. Ask, Which capabilities or skills have you developed since then? Responses might include walking, talking and reading.

Tell students they will be creating timelines of important events in their development. The timelines will include milestones such as the first time they sat up, walked, ran or spoke a word. Remind students that all of these functions are controlled in some way by the brain.

Guide students as they create templates for their timelines. The timelines should include spaces to record at least three important developmental events for each of the first two years of their lifetimes. At least one milestone should be recorded for each subsequent year. Students probably will need to consult their parents or other family members for details about the earliest events. The timelines also should identify whether each milestone was most related to movement, communication, senses, thinking, planning or emotions.

Have students bring their timelines to class to share insmall groups or with the entire class. Ask students if they noticed any similarities in the types of milestones that were most significant in early years of development. In many cases, students will have recorded early events related to basic movements and beginning communication skills. Follow by having students discuss the types of milestones that occurred as they became older. Many of these milestones will be related to thinking, planning, complex movements and types of communication.

Conclude by helping students understand that their brains stillare changing. For example, brain areas involved in judgement and reasoning (frontal lobes of the cerebrum) continue to develop throughout adolescence and into early adulthood. As the brain continues to mature, adolescents develop increased abilities to plan, reason and exercise self-control.